Assassin's Creed Unity may not have been Ubisoft's finest moment, with bugs and more afflicting the title when it released in November 2014.
Plenty of patches have followed to improve performance and Ubisoft also promised a free gift to players - a download of the first DLC pack for everyone who bought the game on PC, PS4 and Xbox One. Dead Kings is an entirely new section of the game, set after Arno's main journey which sees him travelling to the city of Saint Denis.
There he will explore the hidden underground settling beneath the city, uncovering an ancient necropolis and the secrets of the French throne. There are new objects and a new weapon in the form of the Guillotine Gun - which sounds particularly fun to use. Here's some video.
The Dead Kings DLC will come first to Xbox One and PC on the 13th of January, with the PS4 release following on the 14th. Different regions may vary.